Heretofore, attachment rings, or securing devices have been provided on caster stem assemblies but these devices invariably have been made of metal, sometimes steel, but also brass, or copper. These metal inserts between a caster stem and a mounting socket, over a normal period of use, formed corrosion in the assembly and made removal of the stem very difficult. Also, the metal devices frequently would take a permanent set and as a consequence were rendered useless for repeated installations. In some mountings a groove has been formed on the stem and a locking pin was passed through the groove into the mounting to hold the stem in place.
Other mounting arrangements included grooves both on the stem and in the mounting and a metal ring was mounted in the groove on the stem and engaged into the groove in the mounting. Many such mounting arrangements necessitated machining operations on the stem and frequently in the mounting as well. The problems of mounting a caster stem in metal furniture, or the like, are more difficult than where the mounting is made in wood furniture. Metal structures, of course, are more rigid and sometimes lubrication has been restored to in making a caster installation which was undesirable to the ultimate user.
With the metal inserts between the caster stem and a metal mounting socket it was necessary that the entering opening of the socket be chamfered for assembly of the stem and metal device into the socket. Otherwise, entry of the stem assembly into the mounting hole became extremely difficult and necessitated special tools to compress the metal insert device.